Cylinder Pressure Variations of the Fumigated Hydrogen-Diesel Dual Fuel Combustion

Cylinder pressure is one of the main parameters of diesel engine combustion affecting several changes in exhaust gas emission composition and amount as well as engine useful power, specifically when alternative fuels are used. One among other alternative fuels for diesel engine is hydrogen that can be used as fumigated reagent with air prior to intake to engine in order to substitute the main fossil diesel. In this study, experimental investigation was accomplished using a single cylinder diesel engine for agriculture running on different ratios of hydrogen-to-diesel. Cylinder pressure traces corresponding to the crank angle positions were indicated and analyzed for maximum cylinder pressure and their coefficient of variation. The regression analysis is used to find the correlations between hydrogen percentage and the maximum cylinder pressure as well as its coefficient of variation. When higher hydrogen percentages were added, the combustion shifted toward later crank angles with the maximum cylinder pressure decreased and eminent effects at higher load and speed. The plots of hydrogen percentage against the coefficient of variation of the maximum cylinder pressure (COV_Pmax) show the increase in variation of maximum cylinder pressure when the hydrogen percentage increased for all conditions tested. Gaseous hydrogen fumigated prior to intake to the engine reduced maximum cylinder pressure from the combustion while increasing the values of COV_Pmax. The maximum pressure-hydrogen percentage correlations and the COV_Pmax-hydrogen percentage correlations show better curve fittings by second order (n = 2) correlation compared to the first order (n = 1) correlation for all the test conditions.